Articulation sheath for flexible instruments

ABSTRACT

A sheath useful for remote steering, guidance and/or manipulation of a flexible instrument, including e.g. an endoscope, received through the sheath.

BACKGROUND OF THE INVENTION

This invention relates to sheaths for the remote steering, guidance,navigation and manipulation of flexible instruments, such as endoscopes.

Endoscopic procedures typically employ endoscopic instruments that aremaneuvered within or towards a target organ or tissue from a positionoutside the body. Examples of endoscopic procedures includesigmoidoscopy, colonoscopy, esophagogastroduodenoscopy, andbronchoscopy. Typically flexible endoscopes, which have flexibleinsertion tubes, are used for such procedures. The insertion tube of theendoscope is advanced by pushing it forward, and retracted by pulling itback. The tip of the tube may be directed by twisting and generalup/down and left/right movements. Oftentimes, this limited range ofmotion makes it difficult to negotiate acute angles, creating patientdiscomfort and increasing the risk of trauma to surrounding tissues.

Endoscopes can also be employed in laparoscopic procedures. Suchprocedures typically involve introducing a trocar into a person's bodyand then inserting an endoscope tube through the trocar to the desiredlocation. Rigid endoscopes, i.e., endoscopes having a less flexible,more rigid insertion tube (also sometimes referred to as laparascopes)are more typically used in laparoscopic procedures, as the need toadvance such endoscopes through constricted anatomical structures isless pronounced. Maneuverability of the endoscope deployed in thisfashion is limited, with little ability to navigate the endoscopeindependent of moving the insertion trocar.

There have been many attempts to design endoscopes as well as catheters,with improved steerability, however, the range of motion is generallylimited. For example, U.S. Pat. No. 3,557,780 to Sato; U.S. Pat. No.5,271,381 to Ailinger et al.; U.S. Pat. No. 5,916,146 to Alotta et al.;and U.S. Pat. No. 6,270,453 to Sakai describe endoscopic instrumentswith one or more flexible portions that may be bent by actuation of asingle set of wires. The wires are actuated from the proximal end of theinstrument by rotating pinions (Sato), manipulating knobs (Ailinger etal.), a steerable arm (Alotta et al.), or by a pulley mechanism (Sato).U.S. Pat. No. 5,916,147 to Boury et al. discloses a steerable catheterhaving four wires that run within the catheter wall. Each wireterminates at a different part of the catheter. The proximal end of thewires extend loosely from the catheter so that the physician may pullthem. The physician is able to shape and thereby steer the catheter byselectively placing the wires under tension.

Steerable endoscopes have improved range of motion as compared tonon-steerable flexible endoscopes or rigid endoscopes, but their rangeof motion is still generally limited. Further, these devices can belaborious to use, pulling each wires separately as in Boury et al., andmay require a significant amount of training to become proficient inmaneuvering the device through the patient's anatomy, as in the case ofknob and pulley mechanisms. In addition, steerable endoscopes areexpensive to maintain. Consequently, it would be advantageous to providean easier to use, more cost-effective system to improve steering,navigation, guidance and manipulation of conventional flexibleendoscopes.

BRIEF SUMMARY OF THE INVENTION

The present invention provides for a sheath that can receive a flexibleinstrument, e.g., flexible endoscopes, suction tubes, irrigation tubes,and tools with flexible shafts, such as, endoscopic tools (i.e., toolsadapted for delivery through the working channel of an endoscope),lasers and energy sources, and that can route the instrument through thesheath such that a portion of the instrument can extend to or past thedistal end of the sheath. The sheath can be manually manipulated fromits proximal end to remotely steer, guide, manipulate and/or navigatethe insertion tube at the distal end of the sheath.

In one variation of the invention, a sheath is provided having anelongate shaft and proximal and distal sections having multiple pairs oflinks, with one member of a pair located on the proximal section and theother of the pair located on the distal section. The sheath furtherincludes a lumen that extends at least partially through the shaft andwhich opens through the distal section of the shaft. An inlet port incommunication with the lumen is located between the proximal and distalsections of the sheath. The inlet port and shaft lumen allows for theinsertion tube of an endoscope to extend through the sheath to thedistal end of the sheath. The sheath further includes one or more setsof cables connecting the links of at least one discrete pair to oneanother, such that movement of one link of the connected pair causescorresponding relative movement of the other link of the pair. Infurther variations, multiple sets of cables are included, with each setconnecting the links of a discrete pair. Movement of the proximalsection results in corresponding movement of the distal section.

A wide variety of link systems can be used to form the proximal anddistal sections of the sheath. In one variation of the invention, a linksystem is provided where the links form flexible segments. The flexiblesegments comprise a unit of at least one link and at least one flexiblehinge, with adjacent flexible segments joined by flexible hinges. Pairsof flexible segments form the proximal and distal sections. Cablesconnecting the flexible segments of at least one discrete pair to oneanother, such that movement of one flexible segment of the connectedpair causes corresponding relative movement of the other flexiblesegment of the pair

The invention further provides methods of introducing, e.g., a flexibleendoscope into a patient's body by inserting the sheath at a desiredlocation and advancing the endoscope through the inlet port and into thesheath. In certain variations, introduction of the sheath can be aidedthrough the use of a trocar.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a sheath according to one embodiment ofthe invention, in an articulated position, with a flexible endoscopepassing through the sheath;

FIG. 2 is a side view of the sheath of FIG. 1;

FIGS. 2A and 2B are enlarged views of the distal end and proximal endsections of the sheath of FIG. 2 designated 2A and 2B, respectively;

FIGS. 3A-3C show perspective, side, and end views, respectively, of aflexible segment that forms a portion of the distal section of FIG. 2A.

FIG. 4 shows a top view of the sheath and endoscope of FIG. 1, withparts broken away and with the sheath in an unarticulated position;

FIG. 5 shows a top view of the sheath and endoscope of FIG. 1, withparts broken away and with the sheath in an articulated position;

FIG. 6 is a top view of the sheath of FIG. 2;

FIG. 7 is a cross-sectional view of the sheath of FIG. 6 taken along theplane designated by line 7-7;

FIG. 8 is an enlarged cross-sectional view of the portion of the sheathof FIG. 7 designated 8, showing part of the distal section of the sheathin greater detail;

FIG. 9 is an enlarged cross-sectional view of the portion of the sheathof FIG. 7 designated 9, showing part of the handle portion of the sheathin greater detail;

FIG. 10 is an exploded perspective view of the handle portion of thesheath of FIG. 2; and

FIGS. 11A and 11B show side and perspective views, respectively, of thecable guide disposed in the handle portion of FIG. 10.

DETAILED DESCRIPTION

As previously described, sheaths according to the invention areconfigured to receive and pass a flexible instrument through the sheathsuch that the tip of the instrument can emerge from the distal end ofthe sheath. The proximal and distal sections of the sheath are adaptedsuch that movement or articulation of the proximal section producescorresponding movement or articulation of the distal section. Forpurposes of illustration only, such a sheath will now be described withrespect to its use with a flexible endoscope, but it will be understoodthat use with a variety of flexible instruments is contemplated.Typically for use with a flexible endoscope, the sheath can be insertedto a desired location of a patient's body and the flexible endoscope isintroduced into the sheath. Alternatively the endoscope can first beintroduced into the sheath and the combination advanced together.Movement of the distal section of the sheath, which is controlled by theproximal section, moves the tip end of the endoscope insertion tube,thus moving the tip of the endoscope. Thus the endoscope can be easilysteered, maneuvered, and guided by simple manipulation of the proximalsection of the sheath, greatly simplifying navigation of a standardflexible endoscope, and allowing for easy and enhanced maneuverabilityof the endoscope when deployed, e.g., in a patient's body, whether inconventional endoscopic or laproscopic use.

The sheath will typically include an elongate shaft separating theproximal and distal sections. The shaft can be relatively stiff or rigidfor laparoscopic use or it may be more flexible for endoscopic use. Theproximal and distal sections will typically have multiple pairs oflinks, with one member of a pair located on the proximal section and theother of the pair located on the distal section. The terms “link” asused herein refer to a discrete portion or defined area at one end ofthe sheath that corresponds to another discrete portion or defined areaat the opposite end of the sheath. The links are generally, but need notbe cylindrical, and are generally axially aligned relative to oneanother, in an unarticulated condition. In any event, the sheath willinclude a plurality of links or segments that are members of discretepairs, with one link of each pair being situated at the proximalsection, and the other link or segment at the distal section. Sets ofconnecting cables connect the links of a discrete pair to one another sothat movement of one link of a pair causes a corresponding movement ofthe other link or segment in the pair. A variety of link systems andconnecting cables are compatible for forming the proximal and distalsections of the sheath, including but not limited to those described inpending and commonly owned U.S. application Ser. No. 10/444,769, filedon May 23, 2003, U.S. application Ser. No. 10/928,479, filed on Aug. 26,2004, and U.S. application Ser. No. 10/948,911, filed on Sep. 24, 2004,and U.S. application Ser. No. ______entitled “Articulating Mechanismsand Link Systems With Torque Transmission In Remote Manipulation ofInstruments and Tools”, filed Nov. 23, 2004, incorporated herein byreference in their entirety. As used herein, the term “active link” or“active link pair” refers to links that are directly connected to oneanother by a cable set. The term “spacer link” or “spacer link pair”refers to links that are not directly connected by a cable set. Spacerlinks can nevertheless be disposed between active links and provide forthe passage of cable sets that connect active links. The ability toindependently manipulate individual links allows for the proximal anddistal sections to readily form complex three-dimensional configurationsand geometries, in order to easily guide and navigate the endoscopeinsertion tube.

In certain variations of the invention, the proximal and distal sectionsof the sheath will include multiple pairs of flexible segments, such asthose described in commonly owned and pending U.S. application Ser. No.10/948,911, filed on Sep. 24, 2004. Such flexible segments usuallyinclude one or more adjacent links connected by flexible hinges thatbend or flex. A flexible segment capable of movement in two dimensionswith a single degree of freedom can have a single flexible hinge thatconnects two links. Alternatively, two or more flexible hinges canconnect two links where the hinges are aligned in parallel. A flexiblesegment capable of movement in three dimensions with two degrees offreedom can have two flexible hinges oriented at an acute angle to oneanother connecting to three links. For a maximum three-dimensional rangeof motion, the angle will be orthogonal. A flexible segment pair refersto a flexible segment at one end section of the sheath that correspondsto a flexible segment at the other end section of the sheath. In orderto achieve the greatest freedom of motion in three dimensions, at leastone flexible hinge of the sheath is oriented orthogonal to at least oneother hinge of the mechanism. However, the invention also contemplatesconfigurations where flexible hinges are oriented parallel or are offsetat any acute angle. As used herein, the term “active flexible segment”or “active flexible segment pair” refers to flexible segments that aredirectly connected to one another by a cable set. The term “spacerflexible segment” or “spacer flexible segment pair” refers to flexiblesegments that are not directly connected by a cable set. Spacer flexiblesegments can nevertheless be disposed between active flexible segmentsand provide for the passage of cable sets that connect active flexiblesegments.

FIG. 1 depicts an embodiment of a sheath according to the presentinvention with an endoscope deployed through the sheath. Sheath 100includes elongate shaft 150, handle 170, proximal section 125 and distalsection 126. Endoscope 10 includes camera/video coupler 16, port 14 foraccessing the working channel of the endoscope, and insertion tube 12extending from body 15 of the endoscope. Inlet port 172 extends fromhandle 170 and receives insertion tube 12 of endoscope 10. The insertiontube passes through the inlet port 172 and through shaft 150, with thetip of insertion tube 12 exiting from distal section 126 of the sheath.As depicted in FIG. 1, sheath 100 is shown in an articulated position,with the distal section in an articulated position that corresponds tothat o the proximal section. FIG. 2 shows the sheath in the straight,unarticulated configuration.

FIGS. 2A and 2B depict proximal and distal sections 125 and 126 ingreater detail. Proximal and distal sections 125 and 126 are formed of aplurality of flexible segments. Flexible segments 111 and 112, 113 and114, 115 and 116, 117 and 118, 119 and 120, and 121 and 122,respectively, are each members of a discrete pair, with one flexiblesegment of a pair (111, 113, 115, 117, 119 or 121) at proximal section125 with the other (112, 114, 116, 118, 120 or 122) at distal section126. As depicted, flexible segment 111 at proximal section 121 is formedof links 101, 103 and 105 connected by flexible hinges 107 and 109oriented orthogonal to each other. Cable channels are located and passthrough the periphery of each link for accepting passage and connectionof cable sets. The distal section flexible segments also include acentral channel 128 running through the longitudinal axis of theflexible segments of the distal section to accommodate passage of theendoscope, as further detailed herein. Flexible segment 112 is depictedin greater detail in FIGS. 3A-3C, and more clearly depict centralchannel 128 and cable channels 129 of the flexible segments. Pairedflexible segment 112 at distal section 126 similarly is formed of links102, 104 and 106 connected by flexible hinges 108 and 110 orientedorthogonal to one another and likewise include similar cable channelsand can also include a central channel. The remaining flexible segmentsof both the proximal section (113, 115, 117, 119, and 121) and distalsection (114, 116, 118, 120, and 122) have the same configuration withthe last link of one segment also functioning as the first link of thenext segment. And as shown, each flexible hinge is oriented orthogonalto adjacent hinges. As previously noted flexible segments of suchconfiguration move in two degrees of freedom and are moveable in threedimensions. The proximal flexible segments (111, 117, 119 and 121) areconnected to the distal flexible segments (112, 118, 120 and 122) bysets of cables 131, 137, 139 and 141, respectively. These flexiblesegment pairs are thus active flexible segments. Flexible segments 113and 114, and 115 and 116 are not directly connected by a cable set andthus function as spacer segments. The depicted configuration of activeand spacer segments is for illustration only, and it is to be understoodthat arrangements and combinations can vary, depending on theapplication.

Each active flexible segment at the proximal section of the sheath isconnected to its corresponding active flexible segment at the distalsection by at least one and preferably two or more cables. Each cableset may be made up of at least one and preferably two or more cables. Asnoted, movement of one active flexible segment pair is controlled by itscorresponding cable set and is independent of any other flexible segmentpair. In certain variations, for example, a cable set will include threecables spaced 120 degrees apart. By using a set of three cables toconnect an active flexible segment having at least one flexible hingeoriented orthogonal to at least one other flexible hinge, each activeflexible segment pair can be manipulated or moved in three degrees offreedom, independently of any other active pairs. These three degrees offreedom include up/down motion, left/right motion, and rotational or“rolling” motion (whether or not the flexible segment is in a straightor bent configuration). By combining a plurality of active flexiblesegments, multiple degrees of freedom are achieved, allowing theproximal and distal sections of the sheath to be shaped into variouscomplex configurations.

The use of flexible segments in proximal and distal sections 125 and 126has certain advantages. One is simply the flexibility provided by theflexible segments. For even greater flexibility, flexible segmentscombining two flexible hinges between links, such as those described inpending and commonly owned U.S. application Ser. No. 10/948,911, filedon Sep. 24, 2004, incorporated herein by reference in its entirety, maybe used. Another advantage is ease of manufacture and assembly, as theproximal and distal sections can be manufactured as continuous pieceshaving multiple links connected by the flexible hinges. A furtheradvantage is an increased ability to transmit torque along the sheath.However, there are other link systems that can be used in the sheaths ofthe present invention that also transmit torque, including but notlimited to the link systems described in pending and commonly owned U.S.application Ser. No. ______, entitled “Articulating Mechanisms and LinkSystems With Torque Transmission In Remote Manipulation of Instrumentsand Tools”, filed Nov. 23, 2004, incorporated herein in its entirety.

Variations of the sheath can also include proximal section links orsegments that may include a channel for receiving a locking rod that cansecure and retain the proximal end of the sheath in a fixed position.Instead of a rod, a locking sleeve may be fitted over the proximal endof the sheath to secure and retain the proximal end in a fixed position.This may be advantageous in situations where it is desirous to maintainthe endoscope in a fixed location, once it has been steered to thatlocation through use of the sheath. Other mechanisms for locking thesheath in a fixed, articulated position include but are not limited tothose described in U.S. application Ser. No. 10/928,479, filed on Aug.26, 2004, incorporated herein in its entirety.

FIGS. 4 and 5 further show sheath 100 in greater detail with theproximal and distal ends in a straight, unarticulated configuration(FIG. 4) or in a curved, articulated configuration (FIG. 5). As can beseen, distal section exhibits corresponding, inverse movement relativeto the proximal end. Furthermore, the degree of bending or flex of thedistal section is proportionally greater than that of the proximalsection. This proportional scaling of movement is accomplished byincreasing or decreasing the cable channel pattern radius in the linksor flexible segments, at either the proximal or distal end, as isfurther described in pending and commonly owned U.S. application Ser.No. 10/948,911 incorporated herein by reference in its entirety. As canbe seen in FIGS. 4 and 5, the radial distance of the cables from centralaxis of the segments of the proximal section is greater than that in thedistal section. The result is that small, controlled movements outsideof the body allow for a greater degree of movement at the distalsection, which may be advantageous when guiding and navigating aretained endoscope inside the body.

In the proximal and distal sections of sheath 100, there is a one toone, or symmetrical, correspondence of flexible segments. This is notalways necessary and there may be applications where it is desirable fora sheath to have asymmetrical arrangements of links or flexible segmentsat the proximal and distal sections. For example, additional spacerlinks or flexible segments can be added to the proximal or the distalsection, which can be desirable for providing additional length to theproximal or distal sections. In addition the inclusion of additional (ora greater relative number of) of spacer links or flexible segments ateither the proximal or distal section allows for the proportionalscaling of movement or motion of the corresponding other section. Forexample, the inclusion of additional spacer links or flexible segments(or a greater relative number of spacer links or flexible segments) atthe proximal section would require a more exaggerated movement by theuser at the proximal section to achieve the desired motion at the distalsection. This could be advantageous in situations where fine, delicatecontrolled movements were desired, such as, for example, situationswhere there is a risk that a user may not possess the necessarydexterity to perform the desired procedure absent such proportionalscaling of the distal section movement or motion. Alternatively,additional spacer links or flexible segments (or a greater relativenumber of spacer links or flexible segments) could be provided on thedistal section, in which case the degree of distal section movementswould be proportionally greater than those of the proximal end, whichmay also be desirable for particular applications. Spacer links orflexible segments are typically unconstrained, that is, when the distalsection of the sheath, contains the individual spacer links or spacerflexible segments the distal section can not resist movement due tolaterally applied forces (as opposed to active links or flexiblesegments which can be constrained to resist movement due to a laterallyapplied force). Thus, the provision of spacer links or flexible segmentsdecreases the rigidity of the proximal or distal section in those areasthat contain such spacer links or flexible segments, which can bedesirable when navigation of the sheath through or around sensitive orfragile anatomical structures.

As seen in FIGS. 4 and 5, the resulting directional movement of thedistal section 126 is inverted relative to proximal section 125. Inother variations, mirrored movement can be achieved by twisting orrotating the cable sets 180 degrees as they pass through the sheath.Other variations on movement can be achieved by twisting or rotating thecables any amount between 0 to 360 degrees.

Turning now to FIGS. 6-9, it can be seen that shaft 150 includes apassageway for routing a received endoscope. As FIG. 9 shows inparticular detail, handle 170 includes port 172 in communication withinner lumen 154 of shaft tube 152. Shaft tube 152 extends from the inletport into handle 170 and through shaft 150 until it terminates at thedistal end of the shaft where it abuts and is secured to link 106 offlexible segment 122, as shown more clearly in FIG. 8. Alternatively,link 106 could include a counterbore to accept shaft tube 152.Connecting cables, including cables 131, that connect flexible segmentsof proximal and distal sections 125 and 126 enter the handle fromproximal section 125, where they are routed around shaft tube 152,through guide bracket 160, and then through shaft 150 in lumen 151created by the space between the inner wall of shaft 150 and outer wallof shaft tube 152. Guide bracket 160 is positioned in handle 170 to bothcenter and orient shaft tube 152 as it enters the shaft as well as toorient the cables as they are routed around the shaft tube and intolumen 151 of the shaft. At the distal section, link 106 is attached andsecured against both shaft 150 and shaft tube 152. Flexible tube 156extends through the central channel of the flexible segments of distalsection 126 and abuts against shaft tube 154, such that lumen 158 of theflexible tube and lumen 154 of the shaft tube form a continuous lumenfor passing the insertion tube of flexible endoscope that extends frominlet port 172 through handle 170 shaft 150, and distal section 126, andthat opens at the distal end of distal section. Flexible tube 156 issecured to shaft tube 152 and/or link 106 and is otherwise dimensionedto slip fit within central channel 128 (see FIG. 3C) of the flexiblesegments of the distal section, such that when the distal section isbent, the links of the flexible segments that form the distal sectioncan move relative to the flexible tube.

Shaft tube 152 can have variable flexibility or stiffness as it extendsfrom the inlet port 172 and handle 170 through the shaft 150. In certainvariations, the portion of the shaft tube that extends from inlet port172 through the handle will be relatively rigid to aid in guiding theendoscope insertion tube through an initial curved pathway as it travelsfrom the port into the shaft. As the shaft tube extends through theshaft, its relative flexibility or stiffness may vary with that of theshaft. In some instances, it may be desirable for the shaft to berelatively stiff which would in essence supply rigidity to an otherwiseflexible endoscope deployed through the sheath. This might be advantagefor example in laproscopic procedures, where the use of the sheath witha rigid shaft would essentially transform a flexible endoscope into arigid endoscope. In variations where the shaft is flexible, it may befurther advantageous to provide individual lumens to transmit the cablesthrough shaft as an alternative to passing the cables through commonlumen 151. Such a configuration can aid in resisting localized shiftingand splaying of the cables that may result from flexing of the shaft.Flexible tube 156 on the other hand needs to retain adequate flexibilityregardless of the flexibility of the shaft so as not to restrictmovement and articulation of distal section 126. Flexible tube 156 isnot necessary in variations where the distal section uses a link systemwith a fully enclosed central channel. It will be appreciated that theshaft length itself can vary, depending on the application. In certainvariations, the shaft itself can be formed of links or flexiblesegments.

FIG. 10 shows the handle assembly in greater detail. Handle 170 isformed of handle body 174 and handle plate 176 secured together byscrews 175. Handle body 174 includes opening 177 at its proximal end.Flexible segment 121 of proximal section 125 attaches at opening 177.Opening 178 at distal end of handle body 174 is similarly configured forreceipt and attachment of shaft 150 (see FIG. 9). Handle body 170further includes guide slots 186 and 184 (see FIG. 9), and handle plate176 includes guide slot 182, that receive and secure arms of guidebracket 160. Guide bracket 160 is shown in greater detail in FIGS. 11Aand 11B. Guide bracket 160 includes center ring 162 with horizontal andvertical arms 164 and 166, respectively, extending from the center ring.Arm 164 and 166 are secured into guide slots 184, 182 and 186. Shafttube 152 is received through center ring 162 of guide bracket 160 tosupport the tube and orient it for passage into shaft 150. With shafttube 152 in place through the central ring of the bracket, grooves 168together with the outer wall of tube 152 form individual guide channelsto guide and orient the connecting cables as they are routed into lumen151. Alternatively, such guide channels could be integrally formed inface 179 of the distal end of the handle 170. In such a case, acentering channel could also be provided in the face to orient the shafttube 152.

It will be appreciated that while the provision of handle 172 and inletport 172 adds a level of convenience, it is not essential. Alternativevariations of sheaths according to the invention can have the distalsection connect directly to the shaft with the inlet port extending fromthe shaft itself. In other variations, the inlet port need not extendfrom the shaft but can simply be an opening to the lumen of the shafttube that is flush with the shaft surface.

Consistent with the above considerations, the sheath may further be ofany size and shape, as the purpose dictates. Links are generally, butneed not be, cylindrical, and as previously mentioned include channelsfor passage of the cables that connect the flexible segment pairs aswell as passage of the received endoscope. Depending on theapplications, the links and shaft can be dimensioned to accommodatemultiple tubes for receiving multiple instruments through the samesheath. The cable channel diameters are usually slightly larger than thecable diameters, creating a slip fit. For typical endoscopes,representative diameters of links may range from about 1 mm to about 3mm for small endoscopes, about 4 mm to about 8 mm for mid-sizedendoscopes, and about 9 mm to about 15 mm or more for large endoscopes.Overall length of the links will vary, usually depending on the bendradius desired between links. Cable diameters may also vary according tothe application. For typical endoscopic applications, a representativediameter may range from about 0.1 mm to about 3 mm.

The sheath may be formed of a number of materials known in the art andthat can vary according to the application. For ease of manufacture,injection moldable polymers can be used including, e.g., polyethylene orcopolymers thereof, polyethylene terephthalate or copolymers thereof,nylon, silicone, polyurethanes, fluoropolymers, poly (vinylchloride);and combinations thereof, or other suitable materials known in the art.Also, for rigid tubes or shafts, stainless steel can be used.

For certain applications a lubricious coating may be placed on thesheath if desired to facilitate advancement of the sheath. Thelubricious coating may include hydrophilic polymers such aspolyvinylpyrrolidone, fluoropolymers such as tetrafluoroethylene, orsilicones. A radioopaque marker may also be included on the distalsection of the sheath to indicate the location of the sheath uponradiographic imaging. Usually, the marker will be detected byfluoroscopy.

Cable flexibility may be varied, for instance, by the type and weave ofcable materials or by physical or chemical treatments. Usually, cablestiffness or flexibility will be modified according to that required bythe intended application of the sheath. The cables may be individual ormulti-stranded wires made from material, including but not limited tobiocompatible materials such as nickel-titanium alloy, stainless steelor any of its alloys, superelastic alloys, carbon fibers, polymers,e.g., poly (vinylchloride), polyoxyethylene, polyethylene terephthalateand other polyesters, polyolefin, polypropylene, and copolymers thereof;nylon; silk; and combinations thereof, or other suitable materials knownin the art.

The cables may be affixed to the links or flexible segments of an activepair according to ways known in the art, such as by using an adhesive orby brazing, soldering, welding, and the like, including methodsdescribed in pending and commonly owned U.S. application Ser. Nos.10/444,769, 10/928,479, and 10/948,911 incorporated herein by referencein their entirety.

Although the many sheaths that have been illustrated in the accompanyingfigures have a certain number of flexible segments and flexible segmentpairs, this is solely for the illustrative purposes. Any number of linksand link pairs or flexible segments and flexible segment pairs may beemployed, depending on such factors as the intended use and desiredlength of the sheath.

All publications, patents, and patent applications cited herein arehereby incorporated by reference in their entirety for all purposes tothe same extent as if each individual publication, patent or patentapplication were specifically and individually indicated to be soincorporated by reference. Although the foregoing invention has beendescribed in some detail by way of illustration and example for purposesof clarity of understanding, it will be readily apparent to those ofordinary skill in the art in light of the teachings of this inventionthat certain changes and modifications may be made thereto withoutdeparting from the spirit and scope of the appended claims.

1. A sheath for delivery and navigation of a flexible instrument, thesheath comprising: an elongate shaft; proximal and distal sectionshaving multiple pairs of links, each link of each pair being maintainedin a spaced apart relationship relative to the other link of the pair;one or more sets of cables, with each set connecting the links of adiscrete pair, such that movements of one link of a pair causescorresponding relative movement of the other link of the pair; a lumenextending at least partially through the shaft and opening through thedistal end of the distal section; and an inlet port located between theproximal and distal sections, the inlet port in communication with thelumen, the lumen and inlet port configured for receipt and passage of aflexible instrument.
 2. The sheath of claim 1 wherein said two or moreadjacent links are joined by flexible hinges.
 3. The sheath of claim 2wherein at least one flexible hinge is oriented perpendicular to thelongitudinal axis of the shaft.
 4. The sheath of claim 2 wherein atleast one of the flexible hinges is oriented at an acute angle relativeto at least one other flexible hinge.
 5. The sheath of claim 2 whereinat least one of the flexible hinges is oriented orthogonal to at leastone other flexible hinge.
 6. The sheath of claim 2 wherein the flexiblehinges are oriented parallel to each other.
 7. The sheath of claim 1wherein movement of the proximal section results in correspondingrelative movement of the distal section.
 8. The sheath of claim 7wherein said corresponding relative movement of the distal section isreciprocal to the movement of the proximal section.
 9. The sheath ofclaim 7 wherein said corresponding relative movement of the distalsection mirrors the movement of the proximal section.
 10. The sheath ofclaim 1 wherein pairs of links include channels for receipt and passageof sets of cables associated with adjacent pairs of links.
 11. Thesheath of claim 1 further comprising one or more additional links notconnected by discrete sets of cables.
 12. The sheath of claim 1 whereinthe cables connecting a pair of links are at a different radial distancefrom the center of the first link of the pair as compared to the secondlink of the pair.
 13. The sheath of claim 1 further comprising a lockingmechanism for locking the proximal and distal sections into a fixedposition.
 14. A method of introducing a flexible endoscope to a desiredlocation within a patient's body comprising the steps of: advancing thesheath of claim 1 to a desired location within a patient's body; andadvancing a flexible endoscope through the sheath.
 15. A method of claim14 further comprising the step of manipulating the proximal section ofthe sheath to facilitate movement of the endoscope.
 16. A system forperforming endoscopy comprising: the sheath of claim 1; and an endoscopereceived through the lumen of the sheath and with its distal endextending from the distal section of the sheath.